Immense and ever increasing amounts of solid trash, particularly of a municipal nature, are being generated each day. Disposal problems are growing with equal complexity. Conventional methods of refuse disposal, such as land fill or mere incineration, are becoming prohibitively expensive or creating serious pollution problems.
In particular, land fill areas are becoming fewer in number and further from the sites where the majority of the trash is generated. Incineration, because of national concern over the problems of air pollution, is being looked at with ever increasing skepticism.
Municipalities are, therefore, turning to techniques for processing solid wastes to recover, for resale or reuse, the values contained therein. This reduces the problems of pollution and helps offset the cost of processing the trash.
A general method of processing trash involves segregating the organic matter from the inorganics which includes metals, concrete, bricks, glass and the like.
The organics may be processed for recovery as saleable materials such as paper pulp and the balance pyrolyzed to form char and a gaseous stream containing chemicals, which may be condensed as saleable commodities, and char which has an economic value of its own.
With respect to the inorganic matter, ferrous materials may be separated magnetically prior to or following separation of the organics. The remaining inorganics are comminuted by crushing or grinding into particles of fine size. Some may be separated by screening and others by heavy media separations.
The tails from the treatment of municipal wastes are a mixture of finely divided sundry inorganic materials, the most valuable constituent of which is glass. The balance of inorganic materials include fine metal particles, bone, ceramics, egg shells, brick, rock, cement, and the like. Unless recoverable, the glass in this tailing would have no value other than as filler for asphalt.
In U.S. Pat. No. 4,067,502 where one of us is a patentee, it is disclosed that amines serve as beneficiation reagents for the froth flotation of glass from the inorganic tails. Until the present invention, no other class of compounds have been established to be functional for the same purpose.